Rays LED lights and light meter measurements

[smokinjoe52]

My first post on the OB other than my Intro. I have been designing and building a small grow chamber for my orchids. I have decided to utilize just one 27" x 18" shelf for about 6 or 7 orchids. I have 6 Of Ray's LED lights that can be angled and adjusted in several different ways. I decided to purchase a fairly inexpensive, but highly rated light meter on Amazon.

Ray's LED lights seem to be nicely weighted towards the blue end and the red end. Looking at the manual for the Light meter, it seems that it is NOT, by a long ways, linear over the visible spectrum. Please see .pdf attachment.

I was going to use the standard information for light levels found in many places with orchid light info.

900 - 1500 lumens for Phals
1500 - 300 for Onc.

So, am I measuring WAY less light for Ray's LED lights than what the orchids are actually getting?? The meter reads about 600-700 lumens over the Phal, and 1000 or so over the Onc.

Can anybody on the board correlate light meter readings with Ray' Leds?

It would nice to have a multiplier for the meter readings, correlated to Ray's lights.

Any information regarding this would be appreciated.

I wanted to utilize only Ray's LEDs for their low heat output, and the ability to have 6 of them that are fully adjustable. Initial reading brought the in-tent ambient of 68 degrees to only 73 when I turned on 4 lights and zipped up the tent.

Thanks in advance for any information on this subject.

Joe

[estación seca]

Read more in the forum here about growing plants under lights. Your questions will be answered there. It will take a long time to read and understand. Older measurements designed for other kinds of lamps are not applicable to LEDs.

LEDs emit photons in a very narrow frequency range. They do not emit at most visible frequencies the way incandescent or fluorescent lamps do.

Commercial growers select LEDs with emissions spectra near optimum for chlorophyll absorption. This light is pink and blue and unpleasant to most people, but there is no wasted energy producing photons the plants won't use.

[smokinjoe52]

es,

I believe I have read and understand the spectrum and use of LED lamps such as Ray's. I also understand all of your points.

What I have searched for and not found on this forum is the correlation between suggested lumens for various orchid types and Ray's LED bulbs. I don't believe it is 1:1.

If that information is already posted on the forum, I would appreciate a link, because I can't seem to find it.


Joe

[naoki]

Joe, is this the kind of you are looking for:
Brightness with LED Lights

post #18 has PPFD. If you multiply your fc by 0.14, you can get PPFD (in micromol/m^2/s). Phals can be grown around 50-100 micromol/m^2/s (with 12-13 hours/day). I target around 100 micromol/m^2/s.

lux and fc aren't a good measurement for plants, and PPFD isn't perfect, but it is much better (and the standard for the plant science). 1000 fc of sun light contains 200 micromol/m^2/s. But those recommendation you quoted is for the peak (i.e. noon time) intensity in the greenhouse. With continuous light, you can get away with much lower light.

[estación seca]

The lumen, as used to estimate fitness of fluorescent lights for growing plants, is a measurement that doesn't apply to LEDs.

What matters is how many photons of adequate wavelength are emitted by the fixture. This isn't expressed as lumens for LEDs. There are a number of posts by naoki in the lighting forum, where measuring photon flux and calculating the number of photons emitted is explained at length.

A takeaway for me from these discussions is that, in order to compare an LED to a fluorescent fixture, one must look up data on the component manufacturer's Web site, or measure the photons with some rather expensive meters.

[smokinjoe52]

Thanks Naoki,

Just the info I have been trying to find. I will now take a look at what my meter reads at a distance of 12" under a Ray's led light in a dark room, and go from there. Knowing what the output should be from the lamp, I can calculate my own conversion factor...even though I really don't need to convert it to anything. Just need to know what the meter reading is for a known source at a known distance at a known output.

Keep in mind that my objective is not to measure specifics, buy just to stick the meter by a newly placed plant, see a number, (doesn't matter what the units are) and determine if it is "in range" for that specific plant. That is all I really want to know.

[smokinjoe52]

My grow chamber is now up and running. I thought I would share my little project in case an OB member would like to duplicate it or maybe use some of the components. I can provide Amazon links to most parts if anybody is interested.

My objectives:

Build an environmentally enclosed system to house about 6-7 orchids during the growing season. I wanted to control temperature, humidity and light. I also wanted less (watering) maintenance since we travel quite a bit so I am in the process of converting to SH.

The project pics are attached.

I used an inexpensive greenhouse from Amazon. I only wanted 1 grow shelf, so left 1 "floor" out of the build. Spare parts are shown on the floor. I used some adjustable lights that fit perfectly on the frame of the greenhouse. The third floor center rail was omitted as this is where the lights shine through. No big deal if it was included.

The bottom shelf is used for a humidity tray, a 12v IP55 rated (dust and humidity) fan, and a seed germination pad for newly transplanted orchids. I did put a piece of thick black plastic on the bottom shelf for more support.

Second floor are where the transitioned (from SH) plants are located.

Third floor empty and no center rail.

Fourth (top) floor now houses another fan pulling air up from the orchid area. It also contains an old Radio Shack remote temperature and humidity controller so I can monitor from the upper level of the house.

The entire green house sits in a plastic tray meant for portable dog kennels. (It JUST fits)

So, I fired it up.

The usual temp in the room was 68 degrees. The humidity was 34%

I then turned on 4 lights, both fans, filled the humidity tray, added 4 orchids all in SH saucers.

After running 24 hours, daytime temp stabilizes at 73 degrees, +- 2. The humidity holds fairly steady at around 65%. Maybe +- 5%.

I am getting 2 more LED lights (6 total) so expect a few more degrees rise in daytime temperatures. The room is in the lower level of a walkout ranch, so temps. in the summer time will rise less tan 5 degrees.

It has been running for 5 days now, and it seems to be working just as I had hoped...which usually doesn't happen with most of my projects.

Right now I plan to keep maybe 3 Phals and 3 Onc. so am trying to determine how to utilize the lighting, and if I will need any more for the Onc.

BTW - I measured one of my lamps in a dark room, on a non-reflective surface, 12" from the top of the light sensor and measured 3400 lumens.

As I live in the Midwest, it appears now that my orchids will no longer need to live in 25 - 30% humidity, low temps., and too little light in a house surrounded by trees!

Most surprising, and most welcome is the fact that 6 - 13 watt led lights only bump the temp by 5 degrees (4 lights) and maybe 7-8 degrees when I add the last 2 lights. I was afraid the temp. would be too high in the daytime.

Any comments, questions, suggestions etc. welcomed.

Joe

[naoki]

Looks nice, Joe. The plants will be happier with the higher humidity. Watch out for the temp if the window is going to receive direct sun.

As a side note, I think you mean lux, not lumen. lumen is usually used for the total flux and 1 lux is 1 lumen/m^2 (density). Your measurement is aprpox. similar to mine (in fc).

I use reflective grow tent (to minimize the wasted light), and I agree that heat is the problem. I use LED with much higher efficiencies (means more light and less heat per given electric watt), and I can stuff quite a bit of light now. When I was using fluorescent, thermostatically controlled exhaust fan used to kick-in in the summer, but this lowered the RH quite a bit.

[smokinjoe52]

Yes, I did mean lux, sorry about that.

One thing that has me perplexed, (well, one of many) is that you suggested 50 - 100 micromoles for Phals, but Ray's website says Phals do well around 30 for 12-14 hours/day.

Can you elaborate on that?

I have also added a couple intergeneric oncidiums to my collection. What would you recommend for micromoles in an artificial light environment like my tent? Hopefully I can achieve the number with the 6 lights in the tent.

BTW - My fc multiplier is .1746 :-)

Joe

[wintergirl]

Originally Posted by jbridge758

One thing that has me perplexed, (well, one of many) is that you suggested 50 - 100 micromoles for Phals, but Ray's website says Phals do well around 30 for 12-14 hours/day.

Can you elaborate on that?

I have also added a couple intergeneric oncidiums to my collection. What would you recommend for micromoles in an artificial light environment like my tent? Hopefully I can achieve the number with the 6 lights in the tent.

BTW - My fc multiplier is .1746 :-)

Joe

I can add that oncidiums need slightly more light than a phal but not as much as a vanda or a catt.